Triple Oxygen Isotopes Fractionation Of O₃ Generated From O₂ In A Static System Under Low Temperature Plasma Environment And Model Calculation

The oxygen isotopes have been widely used in geological thermometer, the recode of paleo-climate and tracer of geochemistry. And mass independent fractionation of oxygen has provided a new way for geoscience, like the oxygen isotope composition of meteorite can be applied to the research of the solar system evolution, which is significant for cosmochemists and astrophysicists. However, the research of isotope fractionation is constrained by the theory that the calculation based and the isotope detection technology, which make the simulation experiment of the isotope and establishing a new fractionation theory are still needed. This paper will provide some experimental instruction and theoretical verification from some experimental results.This paper discussed the triple oxygen isotopes fractionation of O3 generated from O2 in a static system via dielectric barrier discharge by simulation experiments and model calculation based on the system dynamics theory, which includes two parts:1) the relationship of the oxygen isotope fractionation, initial pressure of oxygen and the yield of ozone under the fixed voltage of dielectric barriers discharge; 2) the relationship of the oxygen isotope fractionation and the voltage of plasma generated by the discharge under the fixed pressure. The results are following:(1) In the reaction chamber where the ozone was produced from the oxygen, the oxygen atom is conversion in three stock which are oxygen atom, oxygen and ozone. And the isotope composition of the ozone shows that the isotope fractionation is mass independent under the discharge,δ17 O (‰) ≠0.52 × δ18O (‰). The linear relation is clear between the Δ17O and δ18O value,δ18O =2.784 (±0.072)Δ17O-8.205(±1.981), which means the process in the chamber can be described by Rayleigh fractionation.(2) Under the fixed initial oxygen pressure, the Δ17O (O3) is increased with the pressure, and the influence of the pressure on the α17 and α18 is much more significant compared with the ozone yield, which means the concentration of the oxygen atom in the chamber has direct influence on the isotope fractionation which can be explained by the Reservoir-Transport effect that the triple oxygen isotopes fractionation of O3 generated from O2 is still mass dependent, but was influenced back and forth between different oxygen stock.(3) Under the same initial pressure, there is no remarkable difference between the Δ17O (O3) value getting from different voltage of the discharge.(4) The relationship between the α17 and α18 value is always the same at different pressure and voltage of discharge.θ value is closed to 1 means that 17O and 18O follow the same path.(5) The fractionation factor a value has significant correlation with the rate of ozone formation, which means the concentration of oxygen atom can influence the isotope fractionation.